My app won't open when downloaded from the internet

In newer versions of GameMaker: Studio (confirmed in 1.3.1347 and EA 1.99.180) if you publish your game to Mac OS X and share the zip file with others via the internet (as opposed to through the App Store) they will not be able to open the application and will receive a warning message as shown on the following apple support page: File quarantine and malware detection.

Currently the only way for the user to then play the game is to remove the application from quarantine using commands in a terminal window. We will be looking into ways to fix this issue, but for now players of your game will have to do the following:

Download your app as a zip file and extract the file to show the app. (in this example, we'll extract to the downloads folder).

Open a terminal window and run the following two commands (where Downloads\ is your download directory and MyDownloadedApp.app is replaced by the actual file name of the app):

cd Downloads\xattr -d com.apple.quarantine MyDownloadedApp.app

Now run the app. It should no longer be quarantined.

This issue does not affect apps distributed through the App Store or shared using a USB drive. We are working on a way of fixing the issue to prevent the need for these steps.